Bonding method for elastic member and metal, and power transmission device

ABSTRACT

Vulcanizing-bonding is carried out using at least a phenolic resin-based vulcanized adhesive F and a silicon compound-based vulcanized adhesive C. Based on an idea of making a penetration of water through a portion bonded with metal difficult, decreasing the adhesion with metal is prevented by utilizing the phenolic resin-based vulcanized adhesive F through which less water can penetrate than the silicon compound-based vulcanized adhesive C, and can increases a thickness of a membrane. Thereby, EPDM or AEM vulcanizable with a peroxide can be strongly bonded to metal, by forming a two-layered structure of the phenolic resin-based vulcanized adhesive F and the silicon compound-based vulcanized adhesive C. Further, a range of selecting a rubber material as an elastic member to be utilized by bonding to metal can be broadened.

TECHNICAL FIELD

The present invention relates to a method for bonding an elastic member made of an ethylene-propylene-diene copolymer (EPDM) vulcanizable with a peroxide, or an elastic member made of an acryl-ethylene copolymer (AEM) vulcanizable with a peroxide to a metal, and a power transmission device formed using the method.

BACKGROUND ART

There is a power transmission device, such as a pulley device and an electromagnetic clutch, which transmits a rotational motive power of a driving source such as an engine to a rotating device such as a compressor on a passive side. Such a power transmission device is composed of a pulley which rotates by receiving rotational motive power from a driving source and a hub, which is arranged coaxially with this pulley, connected to a rotating shaft of a rotating device to rotate as one piece with the rotating shaft.

Japanese unexamined patent publication No. 2002-364667 describes one example of a power transmission device as follows. In the power transmission device, a hub has a hub-side engaging portion composed of an elastic member connected to an outer periphery portion engaged with a front-side end face of a pulley, while the pulley has a pulley-side engaging portion formed at a position corresponding to the outer periphery portion of the front-side end face. The power transmission device forms a torque-transmitting structure with the hub and the pulley, by allowing to the hub-side engaging portion and the pulley-side engaging portion to engage.

In the past, a synthetic rubber such as a chlorinated butyl rubber has been utilized for an elastic member of such a power transmission device. FIG. 8 is a schematic drawing of a sectional view showing a conventional method for bonding the chlorinated butyl rubber and metal (a hub), wherein a metal, an adhesive (F) mainly composed of phenol, an adhesive (H) mainly composed of a halide, and a chlorinated butyl rubber are laminated in order, and are bonded with a method such as a vulcanizing-bonding method.

SUMMARY OF INVENTIONS

When the chlorinated butyl rubber is utilized for the elastic member of the power transmission device as described above, bonding of the rubber and the metal bond is strong, however there is a problem that the chlorinated butyl rubber has poor wear characteristics. As elastic members with excellent wear characteristics, an elastic member made of an ethylene-propylene-diene copolymer (hereafter referred to as EPDM) and an elastic member made of an acryl-ethylene copolymer (hereafter referred to as AEM), both vulcanizable with a peroxide, are known. However, EPDM and AEM vulcanizable with a peroxide cannot bond to a conventionally-utilized adhesive (H) mainly composed of a halide, and there is a problem that there has not been any effective method of bonding with metal.

Inventors of the present invention found that an effective bonding can be obtained, by applying a silicon compound—(e.g. silane)based adhesive, which was proposed for a fluororubber, to EPDM and AEM. Generally, the silane-based adhesive is supplied for bonding as only the adhesive itself. However, when a saline-water spraying test was carried out using an adhesive where only this silane-based adhesive was utilized, a problem that adhesion of the adhesive rapidly decreases for a relatively short period was found (see a graph shown in FIG. 5).

The present invention was achieved by considering problems of the above-mentioned prior art. A purpose of the present invention is to provide a method for bonding strongly EPDM and AEM vulcanizable with a peroxide to metal. Another purpose is to provide a power transmission device of which wear characteristics are improved by utilizing EPDM or AEM as an elastic member.

In order to achieve the above-mentioned purpose, the present invention employs technical means described in the claims. In other words, the first aspect of the present invention provides a method for bonding an elastic member made of an ethylene-propylene-diene copolymer (EPDM) vulcanizable with a peroxide or an elastic member made of an acryl-ethylene copolymer (AEM) vulcanizable with a peroxide to metal, characterized by utilizing at least a phenolic resin-based vulcanized adhesive (F) and a silicon compound-based vulcanized adhesive (C) to vulcanize and bond.

As the cause, where the adhesion in a case using only the silicon compound-based vulcanized adhesive (C) decreases after spraying saline-water, it was found that the silicon compound-based vulcanized adhesive (C) can easily be penetrated with water due to its structure, water can easily enter into a portion bonded with metal due to difficulty of increasing a thickness of a membrane, and an interface with the adhesive is hydrolyzed and becomes easily released due to the water.

In a study for improving such a mechanism of decreasing the adhesion, based on the idea of reducing a tendency for water to penetrate into the portion bonded with metal, the inventors of the present invention aimed to prevent the adhesion with a metal from decreasing by employing the phenolic resin-based vulcanized adhesive (F) which is less penetrated with water than the silicon compound-based vulcanized adhesive (C), and of which the thickness can become large.

According to the first aspect of the present invention, EPDM or AEM vulcanizable with a peroxide can be strongly bonded with metal, by utilizing a two-layered structure of the phenolic resin-based vulcanized adhesive (F) and the silicon compound-based vulcanized adhesive (C). Further, a range of selecting a rubber material for an elastic member to be utilized by bonding to metal can be broadened.

One embodiment of the first aspect of the present invention provides a method for bonding an elastic member to metal, characterized by laminating the metal, the phenolic resin-based vulcanized adhesive (F), the silicon compound-based vulcanized adhesive (C), and the ethylene-propylene-diene copolymer (EPDM) or the acryl-ethylene copolymer (AEM) in order, and bonding them.

According to the embodiment of the first aspect of the present invention, it is possible to reduce the tendency of being penetrated with water into the portion bonded with metal, by forming a layer of the phenolic resin-based vulcanized adhesive (F) between the silicon compound-based vulcanized adhesive (C) and the metal, and to strongly bond EPDM or AEM vulcanizable with a peroxide to the metal.

Another embodiment of the first aspect of the present invention provides a method for bonding an elastic member to metal described in the above-mentioned embodiment, further characterized by that a thickness of each layer of the phenolic resin-based vulcanized adhesive (F) and the silicon compound-based vulcanized adhesive (C) is from 3 to 15 μm. Based on the embodiment of the present invention, it is possible to obtain good adhesion.

Another embodiment of the first aspect of the present invention provides a method for bonding an elastic member to metal described in the above-mentioned embodiment, further characterized by a surface roughness Rz of the metal is from 3 to 12.5. According to the embodiment of the present invention, it is possible to obtain good adhesion.

The second aspect of the present invention provides a power transmission device for transmitting a rotational motive power of a driving source to a rotating device (7) at a passive side, comprising

a pulley (1) which receives a rotational motive power from a driving source to rotate, and

a hub (2) which is arranged coaxially with the pulley (1), and is connected to a rotating shaft (3) of the rotating device (7) to rotate as one piece with the rotating shaft (3),

wherein the hub (2) has a hub-side engaging portion (24) composed of an elastic member connected to an inner-periphery face side or an outer-periphery face side, or an inner- and outer-periphery face sides of an outer periphery portion (23) engaged with a front-side end face of the pulley (1),

the pulley (1) has a pulley-side engaging portion (12) formed on the front-side end face corresponding to the outer periphery portion (23) of the hub (2), and

a torque-transmitting structure of the hub (2) and the pulley (1) is formed by allowing the hub-side engaging portion (24) and the pulley-side engaging portion (12) to engage,

characterized by

utilizing an elastic member made of an ethylene-propylene-diene copolymer (EPDM) vulcanizable with a peroxide or an elastic member made of an acryl-ethylene copolymer (AEM) vulcanizable with a peroxide for the hub-side engaging portion (24), and

bonding the hub (2) made of metal and the hub-side engaging portion (24) with a method for bonding an elastic member to metal according to the first aspect of the present invention.

According to the second aspect of the present invention, a power transmission device with excellent wear characteristics can be obtained.

The third aspect of the present invention provides a power transmission device for transmitting a rotational motive power of a driving source to a rotating device (7) at a passive side, comprising

a pulley (1) which receives a rotational motive power from a driving source to rotate, and

a hub (2) which is arranged coaxially with the pulley (1), and is connected to a rotating shaft (3) of the rotating device (7) to rotate as one piece with the rotating shaft (3),

wherein the hub (2) is composed of an inner hub (21) connected to the rotating shaft (3),

an outer hub(23) engaged to a front-side end face of the pulley (1),

a torque-transmitting elastic member (22) connected to both of the inner hub (21) and the outer hub(23) by intervening between the both hubs (21, 23), and

a hub-side engaging portion (24) formed at the outer hub(23),

the pulley (1) has a pulley-side engaging portion (12) formed at a position corresponding to the outer hub(23) of the front-side end face, and

-   -   a torque-transmitting structure of the hub (2) and the pulley         (1) is formed by allowing the hub-side engaging portion (24) and         the pulley-side engaging portion (12) to engage,     -   characterized by     -   utilizing an elastic member made of an ethylene-propylene-diene         copolymer (EPDM) vulcanizable with a peroxide or an elastic         member made of an acryl-ethylene copolymer (AEM) vulcanizable         with a peroxide for the torque-transmitting elastic member (22),         and     -   bonding the both hubs (21, 23) made of metal and the         torque-transmitting elastic member (22) with a method for         bonding an elastic member to metal according to the first aspect         of the present invention.

The fourth aspect of the present invention provides a power transmission device for transmitting a rotational motive power of a driving source to a rotating device (7) at a passive side, comprising

-   -   a pulley (1) which receives a rotational motive power from a         driving source to rotate, and     -   a hub (2) which is arranged coaxially with the pulley (1), and         is connected to a rotating shaft (3) of the rotating device (7)         to rotate as one piece with the rotating shaft (3),     -   wherein the pulley (1) has an electromagnetic coil (30)         generating an electromagnetic force via an electricity,     -   the hub (2) is composed of an inner hub (60) connected to the         rotating shaft (3),     -   an armature (50) receiving a rotational motive power of the         pulley (1) by being adsorbed to the pulley (1) via an         electromagnetic force generated by the electromagnetic coil         (30), and     -   a spring-plate member (61) in a shape of a circular plate which         is connected to the inner hub (60), and generates a spring force         in a direction of estranging the armature (50) from the pulley         (1), and     -   the armature (50) and the spring-plate member (61) are directly         connected via an elastic member (63),     -   characterized by     -   utilizing an elastic member made of an ethylene-propylene-diene         copolymer (EPDM) vulcanizable with a peroxide or an elastic         member made of an acryl-ethylene copolymer (AEM) vulcanizable         with a peroxide for the elastic member (63), and     -   bonding the armature (50 and the spring-plate member (61)) made         of metal and the elastic member (63) with a method for bonding         an elastic member to metal according to the first aspect of the         present invention.

According to the third and fourth aspects of the present invention, it is possible to obtain a power transmission device with excellent durability. By the way, a number in parentheses attached to each above-described means is one example demonstrating a corresponding relation with concrete means described in embodiments explained hereafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a drawing of a front view to illustrate a power transmission device in the first Embodiment of the present invention.

FIG. 2 shows a longitudinal sectional drawing to illustrate the power transmission device of FIG. 1.

FIG. 3 shows a drawing of a perspective view to illustrate a hub 2 of the power transmission device shown in FIGS. 1 and 2.

FIG. 4 shows a schematic sectional drawing to illustrate a method of bonding an elastic member and metal in one Embodiment of the present invention.

FIG. 5 shows a graph to demonstrate a rate of change of adhesion against a period of saline-water spraying.

FIG. 6 shows a longitudinal sectional drawing to illustrate an electromagnetic clutch 100 in the second Embodiment of the present invention.

FIG. 7 shows a drawing of a front view to illustrate a spring-plate member 61 shown in FIG. 6, wherein a bonded area is shown by hatching.

FIG. 8 shows a schematic sectional drawing to illustrate a conventional method of bonding an elastic member and metal.

DETAILED DESCRIPTION First Embodiment

A power transmission device which is an Embodiment according to the present invention is explained in detail as follows, based on the Figures attached hereto. FIG. 1 is a drawing of a front view to illustrate a power transmission device in the first Embodiment of the present invention. FIG. 2 is a longitudinal sectional drawing to illustrate the power transmission device of FIG. 1. FIG. 3 is a drawing of a perspective view to illustrate a hub 2 of the power transmission device shown in FIGS. 1 and 2.

The power transmission device of the present invention is preferably incorporated into a rotating device 7 such as a compressor of an air-conditioner for vehicles, which rotates by receiving a rotational motive power from a driving source such as an engine or a motor. The power transmission device transmits the rotational motive power (a rotational torque) between a pulley 1 as a driving-side rotating member obtaining a driving from a driving source, and a hub 2 as a following-side rotating member fixed to a shaft (a rotating shaft) 3 of the compressor 7. These pulley 1 and hub 2 are installed on the same shaft.

The pulley 1 is mounted rotatably in a cylindrical portion 4 a installed at one side of a housing 4 of the compressor 7 via a bearing 5 as a bearing device. The pulley 1 is preferably formed with a thermoplastic synthetic resin, but may be formed with a metal material such as iron. When the pulley 1 is made of a resin, the pulley 1 and the bearing 5 are usually formed as one piece by an insert-molding method.

A belt, not shown in the Figure, is wound on an outer periphery face of the pulley 1, and rotates via a motive power from an outside member such as an engine or a motor. The bearing 5 fits into the cylindrical portion 4 a, and is prevented from moving in a direction of the shaft by a snap-ring 5 a as a fixing ring fitted into a groove formed at the outer periphery face of the cylindrical portion 4 a. The housing 4 and the shaft 3 are sealed by a shaft-sealing member 6 a as a shaft-sealing device, and prevent a refrigeration medium or oil from leaking.

A tip end portion 31 of the shaft 3 in the compressor 7 protrudes from the housing 4, and a screw portion is formed at the outer periphery face of the tip end portion 31. Further, a cylindrical hub 2 is fixed on the tip end portion 31 via screw-engaging. For fixing the hub 2 to the shaft 3, other fixing methods such as spline-engaging or fixing with a bolt can be utilized. The item “8” is a washer.

The hub 2 is configured with an inner hub 21, a damper rubber 22 as the elastic member for torque-transmitting, and an outer hub 23, as well as a hub-side engaging portion 24. The inner hub 21 is composed of a cylindrical portion 21 a screw-engaged to the tip end portion 31 of the shaft 3, a cylindrical flange portion 21 c which protrudes toward a front side (a left side in FIG. 2) and of which an outer periphery face is connected to the damper rubber 22, and a discal intermediate portion 21 b connecting the cylindrical portion 21 a and the flange portion 21 c.

At an inner-periphery face of the cylindrical portion 21 a, a screw portion is formed. The inner hub 21 is formed with a metal material such as iron. The outer hub 23 has a cylindrical shape, and is formed with a metal material such as iron in the same manner as the inner hub 21. The annular damper rubber 22, which is the elastic member for torque-transmitting, is formed with the elastic member of a rubber material such as EPDM, AEM and chlorinated butyl, and is maintained by intervening between the inner hub 21 and the outer hub 23. Further, it is connected to the outer periphery face of the flange portion 21 c of the inner hub 21 and the inner periphery face of the outer hub 23 via bonding means.

The damper rubber 22 functions not only as the elastic member for torque-transmitting, but also as a torque damper. A first hub-side engaging portion 24 a is installed at an inner periphery face 23 a of a rear side of the outer hub 23 (a right side in FIG. 2, an upper side in FIG. 3), and a second hub-side engaging portion 24 b is installed at an outer periphery face 23 b, over the approximately whole periphery of the outer hub 23.

The first and second hub-side engaging portions 24 a and 24 b are formed from the elastic member of the rubber material such as EPDM and AEM, and their outer shapes are in a state of unevenness such as an involute-spline and a trochoid. These first and second hub-side engaging portions 24 a and 24 b are respectively connected to each periphery face of the outer hub 23 by bonding. The bonding method of the damper rubber 22 and the both hubs 21, 23, and the bonding method of the hub-side engaging portion 24 and the outer hub 23 are described in detail later, since they are important to the present invention.

The hub-side engaging portion 24 may be installed either at the inner periphery face 23 a or at the outer periphery face 23 b of the outer hub 23. Alternatively, as shown in FIG. 2, the first and second hub-side engaging portions 24 a and 24 b and the damper rubber 22 may be united in one piece so that the first and second hub-side engaging portions 24 a and 24 b wrap a rear-side portion of the outer hub 23. Further, a hub 2, which has no damper rubber 22, and comprises a torque-limiter portion which is broken on a priority basis when too large a torque occurrs, may be utilized.

On the other hand, an annular concave portion 11 to receive the hub-side engaging portion 24 at a front-side face also may be formed at the pulley 1. At an inner-side face 11 a and an outer-side face 11 b of the annular concave portion 11, a first pulley-side engaging portion 12 a and a second pulley-side engaging portion 12 b with outer shapes in an uneven shape such as an involute-spline and a trochoid are formed.

These first and second pulley-side engaging portions 12 a and 12 b also may be formed with the elastic member of a rubber material such as EPDM and AEM, and may bond to the inner face 11 a or the outer face 11 b of the annular concave portion 11. The pulley-side engaging portion 12 may be formed either at the inner face 11 a or at the outer face 11 b of the annular concave portion 11.

In this manner, the first hub-side engaging portions 24 a and the first pulley-side engaging portion 12 a are engaged together by fitting the hub-side engaging portion 24 into the annular concave portion 11 of the pulley 1, and the hub 2 and the pulley 1 are connected together by allowing the second hub-side engaging portion 24 b and the second pulley-side engaging portion 12 b to engage together.

In the above explanation, the peripheries of the hub-side engaging portion 24 and the outer hub 23 are formed in a shape of a continuous circular ring. However, as shown in FIG. 1 or the drawing of a perspective view of the hub 2 in FIG. 2, for the hub-side engaging portion 24 and the rear-side portion of the outer hub 23 may be arranged so that plural slits 25 are formed at regular intervals as appropriate in a peripheral direction.

By forming the hub-side engaging portion 24 and the rear side portion of the outer hub 23 in a shape of plural divided structures in this manner, a cheap, compact and lightweight power transmission device, with no problem of interference between the pulley 1 and the hub 2, may be obtained, by allowing a rib 11 c to correspond to the slit 25, at also a pulley structure where the rib 11 c as a reinforcing portion is formed in a radial direction on a bottom face of the concave portion 11 of the pulley 1 (see FIG. 1), in the pulley 1 composed of a material such as, for example, a resin of which the strength is respectively less than the metal of the pulley 1.

The characteristics and an effect of this Embodiment will be described. FIG. 4 is a schematic sectional drawing to illustrate a method of bonding an elastic member and metal in one Embodiment of the present invention. In the method for bonding EPDM (an elastic member of ethylene-propylene-diene copolymer vulcanizable with a peroxide) or AEM (an elastic member of acryl-ethylene copolymer vulcanizable with a peroxide) to metal, vulcanizing-bonding is carried out by utilizing at least the phenolic resin-based vulcanized adhesive F and the silicon compound-based vulcanized adhesive C.

Concrete examples of the phenolic resin-based vulcanized adhesive F include, for example, CHEMLOCK 205 and CHEMLOCK 200 commercially available from Road Co. and the like. Concrete examples of the silicon compound-based vulcanized adhesive C include, for example, CHEMLOCK 608 and AP133 commercially available from Road Co. and the like. FIG. 5 is a graph to demonstrate a rate of change of adhesion against a period of saline-water spraying.

Based on this, as recognized from the graph, it is possible to strongly bond EDDM or AEM vulcanizable with a peroxide to metal, by forming a two-layered structure of the phenolic resin-based vulcanized adhesive F and the silicon compound-based vulcanized adhesive C. Further, a range of selecting a rubber material as an elastic member to be utilized by bonding to metal can be broadened.

The metal, a phenolic resin-based vulcanized adhesive F, a silicon compound-based vulcanized adhesive C, and EPDM or AEM are laminated in order, and are bonded. Thereby, it can be made difficult for water to penetrate into a portion bonded with metal, and it is possible to strongly bond EDDM or AEM vulcanizable with a peroxide to metal, by forming a layer of the phenolic resin-based vulcanized adhesive F between the silicon compound-based vulcanized adhesive C and the metal.

The thicknesses of layers of the phenolic resin-based vulcanized adhesive F and the silicon compound-based vulcanized adhesive C are respectively in a range from 3 to 15 μm. The surface roughness Rz of the metal is from 3 to 12.5. Based on these characteristics, a good adhesion can be obtained in the present invention.

The elastic member of EPDM or AEM are used at the hub-side engaging portion 24, and the hub 2 and the hub-side engaging portion 24 are bonded by utilizing the above-mentioned bonding method of the elastic member and the metal. Thereby, it is possible to obtain a power transmission device with excellent wear characteristics. Further, EPDM or AEM also are used for the damper rubber 22, and both hubs 21 and 23 made of metal and the damper rubber 22 are bonded by utilizing the above-mentioned bonding method of the elastic member and metal. Thereby, it is possible to make a power transmission device with excellent wear characteristics.

In the power transmission device where EPDM or AEM was utilized for the hub-side engaging portion 24, when a resonance of an auxiliary device and a resonance of a rubber are close, it is preferred to use the chlorinated butyl for the damper rubber 22. When the resonance of an auxiliary device and the resonance of a rubber are different, it is preferred to use AEM for the damper rubber 22. When the resonance of an auxiliary device and the resonance of a rubber are low, it is preferred to use EPDM for the damper rubber 22.

Second Embodiment

FIG. 6 is a longitudinal sectional drawing to illustrate an electromagnetic clutch 100 in the second Embodiment of the present invention. FIG. 7 is a drawing of a front view of the spring-plate member 61 shown in FIG. 6, wherein a bonded area is shown with hatching. This Embodiment shows an Example where the present invention was applied to an electromagnetic clutch 100 to be mounted into a compressor 7 of a refrigerating cycle for an air-conditioner of a vehicle.

The electromagnetic clutch 100 comprises an electromagnetic coil installed in a stator 20, a rotor 40 as a driving-side rotating member to be rotatably driven by an engine for vehicles (not shown in the Figure), an armature 50 to be adsorbed to the rotor 40 via an electromagnetic force generated by the electromagnetic coil 30, and a hub 6 as a following-side rotating member which is connected to this armature 50 and rotates with the armature 50 as one piece. This hub 6 is connected to the shaft 3 of the compressor 7, and transmits the rotational motive power to the compressor 7.

The stator 20 is formed with a magnetic material in a sectional shape of the mark “

” and the electromagnetic coil 30 is installed in this stator 20. The electromagnetic coil 30 is electrically insulated and fixed by molding in the stator by an insulating resin member such as epoxy. The stator 20 is fixed in the housing 4 of the compressor 7 via a supporting member 9 in a shape of a ring.

The rotor 40 has a pulley 41 a where a multi-stage typed V-belt, not shown in the Figure, is looped over its outer periphery portion, and rotates by a rotational motive power transmitted from an engine via the V-belt. The rotor 40 is formed with a magnetic material such as iron, in a sectional shape of the mark “

” installing the stator 20 via a small gap with the stator 20. The rotor 40 comprises a bearing 5 at its inner periphery, and is supported ratatably on the outer periphery face of a cylindrical boss portion 4 a of a compressor-housing 4 via this bearing 5.

The armature 50 is arranged opposite to a frictional surface of the rotor 40 at a distance of desired small gap (e.g. about 0.5 mm), and is formed with a magnetic material such as iron in a ring shape. The armature 50 of this Example forms a groove portion for magnetically dividing an inner side ring portion and an outer side ring portion, not shown in the Figure. The inner side ring portion and the outer side ring portion are connected as one piece via a bridge portion (a connecting portion) between the groove portions, by dividing this groove portion into plural pieces in a circumferential direction.

Then, the hub 6 is explained in detail. The hub 6 has an inner hub 60 cylindrically formed with an iron-based metal wherein a spline-engaging portion 60 a is formed at an inner-periphery face of the cylindrical portion of the inner hub 60, and is engaged to the shaft 3 in one piece in a rotational direction at this spline-engaging portion 60 a. Installing-flange portions 60 b extending outside in a radial direction from one end portion of a cylindrical portion of the inner hub 60 in a direction of the shaft (the left end portion in FIG. 6) are formed in one piece at three positions in a circumferential direction.

A following-side connecting portion 61 a at the inner-periphery portion of the spring-plate member 61 (FIG. 7) is connected to these three installing-flange portions 60 b via three rivets 62. This spring-plate member 61 is configured with a spring material made of an iron-based metal, and its whole shape is formed in a shape of a circular plate as shown in FIG. 7.

A ring portion 60 c, which protrudes in a ringed shape toward inside in a radial direction from one end portion of a cylindrical portion of the inner hub 60 in a direction of the shaft (the left end portion in FIG. 6), is formed. This ring portion 60 c is tightly fixed to a tip end portion of the shaft 3 with a bolt 10. Thereby, the hub 6 can be connected to the shaft 3 in one piece.

In the spring-plate member 61, as shown in FIG. 7, plate-spring portions 61 b extending in a radial direction are formed at three positions between the following-side connecting portion 61 a of the inner-periphery portion. More concretely, a connecting portion via the rivet 62, and a outer-periphery ring portion 61 f. Therefore, the longitudinal direction of the plate-spring portion 61 b is arranged to point in the radial direction.

In order to form these plate-spring portions 61 b, notched grooves 61 c, which compartment both sides in the circumferential direction of the plate-spring portions 61 b, are formed. Herein, the notched groove 61 c is in a shape of a curvature, and has groove portions 61 d, which are located at one side in a circumferential direction of the adjoining plate-spring portions 61 b, and an intermediate groove portion 61 e which connects these groove portions 61 d together. The curvature is formed so that the intermediate groove portion 61 e can position at the most inner periphery side.

Tip end portions of the outer periphery side of the above-mentioned plate-spring portions 61 b located at three positions are connected to the outer-periphery ring portion 61 f in one piece. Therefore, the spring-plate member 61 is formed in one piece so that portions from the following-side connecting portion 61 a of the inner-periphery portion to the outer-periphery ring portion 61 f can form one circular plate.

By the way, in this Embodiment, the curved shape of the notched groove 61 c is formed so that the intermediate groove portion 61 e of the notched groove 61 c can be positioned further inside than the inner-periphery face of the armature 50. Thereby, a broad portion 61 g which expands an area of the outer-periphery ring portion 61 f can be formed at the mutual intermediate portion of the three plate-spring portions 61 b. Further, the most inner periphery portion of the broad portion 61 g can be extended to more inner side than the inner periphery face of the armature 50.

Then, the spring-plate member 61 and the armature 50 have approximately the same outer diameter, and the elastic member 63 directly connecting the spring-plate member 61 and the armature 50 is installed between them. The elastic member 63 is formed from a rubber-based elastic material, and as shown in FIG. 6, has a shape of a ringed plate corresponding to the ringed shape of the armature 50. The elastic member 63 is bonded (fixed) in one piece to both of the spring-plate member 61 and the armature 50 through a method of vulcanizing-bonding (baking-bonding) in a desired molding tool.

More concretely, for the armature 50, the elastic member 63 is entirely bonded to the inner ring and the outer ring. However, for the spring-plate member 61, the elastic member 63 is baked and bonded only to portions closer to the outer periphery than the notched groove 61 c, in other words, portions of the outer-periphery ring portion 61 f and the broad portion 61 g as shown with small dots in FIG. 7.

Therefore, for the spring-plate member 61, even at a portion positioned at more outer periphery side than the inner-periphery face of the inner ring of the armature 50, the elastic member 63 is not baked and bonded at the following-side connecting portion 61 a and the plate-spring portion 61 b. This aims to prevent that elastic deformation of the plate-spring portion 61 b is inhibited by the bonding of the elastic member 63.

In the step of baking and bonding, it can be easily prevented to bond the elastic member 63 to the following-side connecting portion 61 a and the plate-spring portion 61 b, by employing a method for masking a coating of an adhesive applied to the following-side connecting portion 61 a and the plate-spring portion 61 b. For a rubber material utilized for the elastic member 63, a material which demonstrates excellent properties for torque-transmitting and torque-change absorbing (vibration-damping) against a wide variation of the ambient temperature for vehicles (from −30° C. to 120° C.), is preferred.

Concretely, an elastic member made of an ethylene-propylene-diene copolymer (EPDM) vulcanizable with a peroxide or an elastic member made of an acryl-ethylene copolymer (AEM) vulcanizable with a peroxide is utilized. For bonding the elastic member, it is carried out to vulcanize and bond it as a two-layered structure of the phenolic resin-based vulcanized adhesive and the silicon compound-based vulcanized adhesive (wherein the phenolic resin-based vulcanized adhesive is used at a metal side).

Three holes 61 h of the spring-plate member 61 are used in order to insert a pin (not shown in the Figure), press it to the armature 50, and keep the armature 50 at a desired position in the molding tool, when the vulcanizing-bonding step is performed. In the same manner, three holes 51 of the armature 50 are used to insert a pin (not shown in the Figure), to press it to the spring-plate member 61, and keep the spring-plate member 61 at a desired position in the molding tool, when the vulcanizing-bonding step is performed.

In this Embodiment, as thin-film covering portions 63 a and 63 b, which respectively cover the inner periphery face and the outer periphery face of the armature 50, are formed as one piece with the elastic member 63, it is possible to allow these thin-film covering portions 63 a and 63 b to hold also the same surface-protective action as a surface-treated layer. Therefore, the surface-treating step for the armature 50 may become unnecessary.

Next, an operation of this Embodiment with the above-mentioned constitution is explained. At the time of stopping electricity of the electromagnetic coil 30 (during turning the clutch “off”), the armature 50 is maintained at a position with a desired distance from a frictional surface of the rotor 40 via a spring force of the plate-spring portion 61 b of the spring-plate member 61. Thereby, a rotational motive power from an engine of a vehicle (not shown in the Figure) is transmitted only to the rotor 40 via a V-belt, but not transmitted to the armature 50 and the hub 6. Therefore, only the rotor 40 spins on the bearing 5, and the compressor 7 is stopped.

On the other hand, when electricity is passed through the electromagnetic coil 30, the armature 50 is sucked to the rotor 40 against the spring force of the plate-spring portion 61 b of the spring-plate member 61, via an electromagnetic force generated by the electromagnetic coil 30. Further, the armature 50 is adsorbed to the rotor 40. Then, a rotation of the rotor 40 is transmitted to the shaft 3 of the compressor 7 through the armature 50, the elastic member 63, the spring-plate member 61 and the inner hub 60, and the compressor 7 is operated. When the electricity to the electromagnetic coil 30 is shut off, the armature 50 returns to the original estranging position via the spring force of the plate-spring portion 61 b of the spring-plate member 61, by extinction of the electromagnetic force, and the compressor 7 returns to the stopped state.

By the way, bonding is carried out by allowing the elastic member 63 to intervene between the armature 50 and the outer-periphery ring portion 61 f of the spring-plate member 61. Therefore, in a step of adsorbing the armature 50 to the rotor 40 at the above-mentioned period of turning the clutch “On”, a shock and a vibration caused by adsorbing the armature to the frictional surface of the rotor 40 can be reduced by a vibration-damping action of the elastic member 63. In the same manner, a torsion-resonance related to a driving-torque change of the compressor 7 also can be relaxed by a vibration-damping action of the elastic member 63. By these vibration-damping actions of the elastic member 63, operating noises of the electromagnetic clutch 100 and the compressor 7 can be effectively reduced.

Further, a returning movement of the armature 50 in the direction of the shaft during turning the clutch “Off” can be carried out by the spring force of the plate-spring portion 61 b of the spring-plate member 61. Therefore, it is not necessary to allow the elastic member 63 to hold also a spring action for the returning movement of the armature 50 in the direction of the shaft. Thereby, the elastic member 63 can be formed in the shape of a thin plate along the radial direction of the armature 50 and the outer-periphery ring portion 61 f of the spring-plate member 61. Further, a dimension of the elastic member 63 in the direction of the shaft (a thickness of the plate) can be, for example, about 2 mm, and can be significantly decreased in comparison with a dimension of a conventional cylindrical elastic member in the direction of the shaft (generally, about 10 mm).

When a locking phenomenon of the compressor 7 happens for any reason, the hub 6 and the armature 50 connected to the shaft 3 of the compressor 7 becomes unable to rotate, and thereby the rotor 40 rotates with sliding against the armature 50. As a result, the frictional surface between the rotor 40 and the armature 50 is heated, and a temperature of the elastic member 63 is elevated.

When the temperature is elevated to a meltdown temperature which is determined by a material of the elastic member 63, the elastic member 63 melts, and a state of connecting the armature 50 and the spring-plate member 61 is stopped. Therefore, after that, the armature 50 remains to be adsorbed to the rotor 40, the rotor 40 rotates as one piece with the armature 50, and the torque transmission between the armature 50 and the spring-plate member 61 is shut off. Therefore, a state of overloading due to the locking phenomenon of the compressor 7 is cancelled. Thereby, an occurrence of a problem such as cutting a belt and an abnormal elevation of the temperature due to continuation of this overloading state for a long period can be reduced.

Plural plate-spring portions 61 b are formed between the following-side connecting portion 61 a of the inner periphery portion and the outer-periphery ring portion 61 f of the spring-plate member 61 so that they can extend in the radial direction. Thereby, the broadened-width portion 61 g, which expands the area of the outer-periphery ring portion 61 f, can be formed at the mutual intermediate portion of the plural plate-spring portions 61 b.

Thereby, it is possible to enlarge a bonded area between the spring-plate member 61 and the elastic member 63, to increase a bonding strength between both members 61 and 63, and to improve torsional durability of the clutch. The torsional durability can be evaluated using the number of applications of a maximum torque of the compressor, before when applying and releasing of the maximum torque of the compressor are repeated between the armature 50 and the hub 6 (the spring-plate member 61) at desired intervals, the elastic member 63 is broken, and the torque transmission becomes impossible.

In the above-mentioned Embodiment, a configuration of connecting, in one piece, an inside ring portion 5 and an outside ring portion of the armature 50 with a bridge portion (a connecting portion) between plural arc-shaped grooves for electromagnetically shutting off is made, and the whole armature 50 is formed as an one-piece component. However, another configuration may be utilized, where the inside ring portion and the outside ring portion of the armature 50 are formed separately, a groove for electromagnetically shutting off is arranged between the inside ring portion and the outside ring portion, and the inside ring portion and the outside ring portion are bonded in one piece to the spring-plate member 61 through the elastic member 63.

Then, characteristics and an effect of this Embodiment are described. The elastic member made of the ethylene-propylene-diene copolymer (EPDM) vulcanizable with a peroxide or the elastic member made of the acryl-ethylene copolymer (AEM) vulcanizable is utilized for the elastic member 63, and the armature 50 and the spring-plate member 61 made of metal, and the elastic member 63 are bonded using the same bonding method of the elastic member and the metal as in the above-mentioned first Embodiment. Thereby, the power transmission device with excellent durability can be obtained.

The elastic member made of the ethylene-propylene-diene copolymer (EPDM) vulcanizable with a peroxide and the elastic member made of the acryl-ethylene copolymer (AEM) vulcanizable with a peroxide in this Embodiment are respectively the elastic member of an ethylene-propylene-diene copolymer (EPDM) and the elastic member of the acryl-ethylene copolymer (AEM) subjected to non-sulfur crosslinking with an organic peroxide (e.g. PERHEXA 25B from NOF Corporation). In the specification of the present application, “vulcanizable with a peroxide” and “crosslinking with a peroxide” are used as terms of the same meaning.

Other Embodiments

In the above-mentioned Embodiments, the method for bonding the elastic members and the metal in the present invention is applied to the power transmission device. However, the present invention is not limited to the Embodiments, and may also be applied to bonding a metal member of a vibration-insulating device and a rubber vibration insulator. Particularly, it is preferred for a portion to be subjected to a high temperature. Further, a treatment with a phosphite may be utilized as a treatment of a surface of metal. The silane-based adhesive was utilized as the silicon compound-based adhesive in the above-mentioned Embodiments. However, the present invention is not limited to the Embodiments, and any silicon-based compound may be utilized. 

1. A method for bonding an elastic member made of an ethylene-propylene-diene copolymer (EPDM) vulcanizable with a peroxide or an elastic member made of an acryl-ethylene copolymer (AEM) vulcanizable with a peroxide to metal, characterized by utilizing at least a phenolic resin-based vulcanized adhesive (F) and a silicon compound-based vulcanized adhesive (C) to vulcanize and bond.
 2. The method for bonding an elastic member to metal according to claim 1, characterized by laminating the metal, the phenolic resin-based vulcanized adhesive (F), the silicon compound-based vulcanized adhesive (C), and the ethylene-propylene-diene copolymer (EPDM) or the acryl-ethylene copolymer (AEM) in that order, and bonding them.
 3. The method for bonding an elastic member to metal according to claim 1, characterized by that a thickness of each layer of the phenolic resin-based vulcanized adhesive (F) and the silicon compound-based vulcanized adhesive (C) is from 3 to 15 μm.
 4. The method for bonding an elastic member to metal according to claim 1, characterized by a surface roughness Rz of the metal is from 3 to 12.5.
 5. A power transmission device for transmitting a rotational motive power of a driving source to a rotating device (7) at a passive side, comprising a pulley (1) which receives a rotational motive power from a driving source to rotate, and a hub (2) which is arranged coaxially with the pulley (1), and is connected to a rotating shaft (3) of the rotating device (7) to rotate as one piece with the rotating shaft (3), wherein the hub (2) has a hub-side engaging portion (24) composed of an elastic member connected to an inner-periphery face side or an outer-periphery face side, or an inner- and outer-periphery face sides of an outer periphery portion (23) engaged with a front-side end face of the pulley (1), the pulley (1) has a pulley-side engaging portion (12) formed on the front-side end face corresponding to the outer periphery portion (23) of the hub (2), and a torque-transmitting structure of the hub (2) and the pulley (1) is formed by allowing the hub-side engaging portion (24) and the pulley-side engaging portion (12) to engage, characterized by utilizing an elastic member made of an ethylene-propylene-diene copolymer (EPDM) vulcanizable with a peroxide or an elastic member made of an acryl-ethylene copolymer (AEM) vulcanizable with a peroxide for the hub-side engaging portion (24), and bonding the hub (2) made of metal and the hub-side engaging portion (24) with a method for bonding an elastic member to metal according to claim
 1. 6. A power transmission device for transmitting a rotational motive power of a driving source to a rotating device (7) at a passive side, comprising a pulley (1) which receives a rotational motive power from a driving source to rotate, and a hub (2) which is arranged coaxially with the pulley (1), and is connected to a rotating shaft (3) of the rotating device (7) to rotate as one piece with the rotating shaft (3), wherein the hub (2) is composed of an inner hub (21) connected to the rotating shaft (3), an outer hub(23) engaged to a front-side end face of the pulley (1), a torque-transmitting elastic member (22) connected to both of the inner hub (21) and the outer hub(23) by intervening between the both hubs (21, 23), and a hub-side engaging portion (24) formed at the outer hub(23), the pulley (1) has a pulley-side engaging portion (12) formed at a position corresponding to the outer hub(23) of the front-side end face, and a torque-transmitting structure of the hub (2) and the pulley (1) is formed by allowing the hub-side engaging portion (24) and the pulley-side engaging portion (12) to engage, characterized by utilizing an elastic member made of an ethylene-propylene-diene copolymer (EPDM) vulcanizable with a peroxide or an elastic member made of an acryl-ethylene copolymer (AEM) vulcanizable with a peroxide for the torque-transmitting elastic member (22), and bonding the both hubs (21, 23) made of metal and the torque-transmitting elastic member (22) with a method for bonding an elastic member to metal according to claim
 1. 7. A power transmission device for transmitting a rotational motive power of a driving source to a rotating device (7) at a passive side, comprising a pulley (1) which receives a rotational motive power from a driving source to rotate, and a hub (2) which is arranged coaxially with the pulley (1), and is connected to a rotating shaft (3) of the rotating device (7) to rotate as one piece with the rotating shaft (3), wherein the pulley (1) has an electromagnetic coil (30) generating an electromagnetic force via an electricity, the hub (2) is composed of an inner hub (60) connected to the rotating shaft (3), an armature (50) receiving a rotational motive power of the pulley (1) by being adsorbed to the pulley (1) via an electromagnetic force generated by the electromagnetic coil (30), and a spring-plate member (61) in a shape of a circular plate which is connected to the inner hub (60), and generates a spring force in a direction of estranging the armature (50) from the pulley (1), and the armature (50) and the spring-plate member (61) are directly connected via an elastic member (63), characterized by utilizing an elastic member made of an ethylene-propylene-diene copolymer (EPDM) vulcanizable with a peroxide or an elastic member made of an acryl-ethylene copolymer (AEM) vulcanizable with a peroxide for the elastic member (63), and bonding the armature (50 and the spring-plate member (61)) made of metal and the elastic member (63) with a method for bonding an elastic member to metal according to claim
 1. 